title: The bacterial biofilms in dialysis water systems and the effect of the sub inhibitory concentrations of chlorine on them.
abstract: BACKGROUND
  The presence of bacteria in the form of biofilms poses a problem in the fluid pathways of haemodialysis plants and procedures which are aimed to detach and neutralize biofilms are necessary to improve the patient safety and the quality of the healthcare. The present study was therefore aimed at isolating the organisms which colonized dialysis water systems as biofilms, as well as to study the effect of the sub inhibitory concentrations of chlorine on the biofilms which were produced by these isolates.
  
  
  METHODS
  Swabs were used to collect the biofilms which were produced on the internal surface of the dialysis tubing from the dialysis units. This study was conducted at the Department of Microbiology, Kasturba Medical College (KMC), Mangalore, India. The cultures were performed on MacConkey's agar and blood agar. The organisms which were isolated were identified and antibiotic sensitivity tests were performed. The biofilm production was done by the microtitre plate method of O'Toole and Kolter. The biofilm production was also studied in the presence of sub inhibitory concentrations of chlorine.
  
  
  RESULTS
  Acinetobacter spp and Pseudomonas aeruginosa were the two predominant organisms which colonized the dialysis water systems as biofilms. The sub inhibitory concentrations of chlorine did not bring about any decrease in the biofilm production by the isolates. On the contrary, there was an increase in the biofilm production.
  
  
  CONCLUSIONS
  Our study highlighted the importance of using appropriate methods to improve the quality of the water in dialysis units. This in turn, may help in reducing the biofilm formation in the water systems of dialysis units and thus, contribute to the prevention of hospital acquired infections in the patients who need haemodialysis.
authors.affiliation: Associate Professor, Department of Microbiology Kasturba Medical College , Mangalore, Manipal University, Karnataka State, India .
authors.forename: Ethel
authors.initials: E
authors.lastname: Suman
authors.forename: Benji
authors.initials: B
authors.lastname: Varghese
authors.forename: Neethu
authors.initials: N
authors.lastname: Joseph
authors.forename: Kumari
authors.initials: K
authors.lastname: Nisha
authors.forename: M Shashidhar
authors.initials: MS
authors.lastname: Kotian
keywords: Acinetobacter spp; Biofilms; Chlorine; Dialysis water; Pseudomonas aeruginosa